31

Discussions about the products / MOVED: EQ 250 setup question

« Last post by JPK on January 21, 2026, 06:16:01 PM »

This topic has been moved to EQ250 stereo equalizer.

https://www.soundskulptor.com/forum/index.php?topic=7394.0

32

EQ250 stereo equalizer / Re: EQ 250 setup question

« Last post by JPK on January 21, 2026, 06:13:13 PM »

You can use a plugin in your DAW that generates a variable frequency sine wave (there are several free plugins available like tonegenerator) and adjust the frequency for the maximum output signal.

33

EQ250 stereo equalizer / EQ 250 setup question

« Last post by TheWoodman on January 21, 2026, 03:48:27 PM »

Hi, I want to build a 250 stereo EQ and I wonder how to test the left / right balance. The setup manual says: Do the test with the frequency adjustment potentiometer in the middle of the band, at about 12 o’clock. Measure the central frequencies of the two channels. you get fmin and fmax.

My question is: how to measure this? Do I send an audio signal through the unit and turn (for example) the mid band volume up? And then use a frequency analyzer on the computer and look for 'bump' differences in both channels? If I use an audio signal, what kind (white, sine etc)? So, any tips how to do this measurement?

I understand the part about adding caps when channels don't match. My question is how to measure wether they match or not.

34

CP5176 FET compressor / Re: No sound CP5176

« Last post by JPK on January 21, 2026, 11:14:57 AM »

I have put a 1VAC sine 1 Khz signal to the input of the compressor and I don´t get any VAC reading on TP1
Check the solder joints on transformer T1, connectors CN3a and CN3b, potentiometer P1.

With a signal at the input, check that you get an AC volts reading on pot P1 top pin, against 0V, then on TP1 with P1 set at max.

35

CP5176 FET compressor / Re: No sound CP5176

« Last post by Stam on January 20, 2026, 01:33:47 PM »

Hi!

Nr 3 on the checklist:

I have put a 1VAC sine 1 Khz signal to the input of the compressor and I don´t get any VAC reading on TP1, Tp2 and L1.

Nr 4:

I am not a skilled electrician and did not understand input sine 100hz at 100mVAC? Can’t even get that low signal from the software generator so did send a 100Hz at 1VAC instead. Maybe you can teach me there …

Ac level on TP3:
My multimeter read 0.04 VAC on every ratio.

DC level on PT4:
All value where correct on all ratio.

DC level on JMP1 pin 1:
Did not get any reading on any ratio

DC level on TP6:
Did get -2,7 VDC so it seems okey.

DC level on TP5 with jumpers JMP1 on 2-3 and 4-5:
 Was correct, I did get exactly 0.32 VDC

36

MU524 Vari-Mu Tube Compressor / Re: STEP 6 OUT 1Vac

« Last post by JPK on January 20, 2026, 08:56:11 AM »

D'après les photos envoyées, sur le 1er MU524, les trimmers ne sont pas à la bonne place:
TR1 5k au lieu de 2k
TR2 5k au lieu de 1k
TR3 1k au lieu de 5k
TR4 2k au lieu de 5k

37

MU524 Vari-Mu Tube Compressor / Re: STEP 6 OUT 1Vac

« Last post by FX on January 19, 2026, 06:00:22 PM »

IDEM SANS U4

R3=R4=2185 OHM
R5=2225
R6=R7=10K
R8=469

38

CP5176 FET compressor / Re: No sound CP5176

« Last post by JPK on January 19, 2026, 04:13:23 PM »

Every value was right except D: that should be - 0.2 V, and I did get - 0.133 V.
This is probably OK.

You must try to follow the signal as mentioned here.
It will tell you where the signal chain is broken.

39

MU524 Vari-Mu Tube Compressor / Re: STEP 6 OUT 1Vac

« Last post by JPK on January 19, 2026, 03:35:34 PM »

TP1=41,4 VDC
TP2= 40 VDC
Est-ce le même résultat en retirant U4 ?
Vérifier les valeurs et soudures de R3...R8.

40

CP5176 FET compressor / No sound CP5176

« Last post by Stam on January 19, 2026, 12:09:15 PM »

 I have built the main PCB and the front PCB on the CP5176. I connected them and did the setup test. I connected to my 500 box with XT500. Pushed the red button-the green led lighted up. I connected the multimeter black probe to OV and the red probe to the V+. Perhaps I did something wrong and made some connection with something because it came smoke from the area where the red probe sat. Unfortunately (it was late at night) I moved the red prob to the V- test pin and did get another smoke from the big transformer area. I saw that the R57 was burned. I replaced R56 and R57. Started the process again. The green led light up, but it turned off after a while. I measured direct on the replaced resistor R56 volt and it was +16.03v in, and +0.04 v out. On the R57 was -16.12 in and -0.54 v out. They were broken again. I replaced them again and also replaced the two TL074CN Quad Op-Amp. Started up the compressor again. Now I did get the right measurement on V+, V- and on TP7. Everything seems okey so far.
I build the SK25 and put it in place and send the 1khz sinewave to the compressor. Turned the in and out potentiometer up. No signal passed through the compressor. I measured the L1 with DC and did get 0,057 V, and the SK25 became warm after some minutes. Can’t find any misplaced components on the SK25 or obviously bad joints, but something is wrong I suppose. I also did the measurement on the resistors A to G without the SK25 described in the forum: https://www.soundskulptor.com/forum/index.php?topic=402.0  
Every value was right except D: that should be - 0.2 V, and I did get - 0.133 V.
I have also checked this: https://www.soundskulptor.com/forum/index.php?topic=9.0
Can’t find any problem so far. How Should I proceed?